Semiconductor Structure of Cell Array Formed by Cells with Hybrid Cell Heights

CROSS REFERENCE TO RELATED APPLICATIONS

This Application claims priority of U.S. Provisional Application No. 63/116,937, filed on Nov. 23, 2020, and U.S. Provisional Application No. 63/213,308, filed on Jun. 22, 2021, the entirety of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a cell array, and more particularly to a cell array formed by cells with hybrid cell heights.

Description of the Related Art

Integrated circuits (ICs) have become increasingly important. Applications using ICs are used by millions of people. These applications include cell phones, smartphones, tablets, laptops, notebook computers, PDAs, wireless email terminals, MP3 audio and video players, and portable wireless web browsers. Integrated circuits increasingly include powerful and efficient on-board data storage and logic circuitry for signal control and processing.

With the increasing down-scaling of integrated circuits, the integrated circuits become more compact. For various cells that are frequently used in integrated circuits, when the cell height difference increases, the arrangement of the cells becomes more complicated. Therefore, a cell array with hybrid cell height is desired.

BRIEF SUMMARY OF THE INVENTION

Semiconductor structures are provided. An embodiment of a semiconductor structure is provided. The semiconductor structure includes a cell array. The cell array includes a plurality of first cells arranged in a first column, a plurality of second cells arranged in a second column abutting the first column, and at least one third cell arranged in the first column. Each of the first cells has a first cell height along a first direction and is configured to perform a first function. Each of the second cells has a second cell height along the first direction and is configured to perform a second function. The third cell has a third cell height along the first direction and is configured to perform a third function that is different from the first function and the second function. Each of the second cells is coupled to and in contact with a respective first cell, and configured to receive at least one signal from the respective first cell and provide an output signal according to the received signal. The second cell height is greater than the first cell height, and the number of first cells is equal to the number of second cells. The third cell height is proportional to the first cell height.

Furthermore, an embodiment of a semiconductor structure is provided. The semiconductor structure includes a cell array. The cell array includes a plurality of first cells arranged in a first column, a plurality of second cells arranged in a second column abutting the first column, at least one third cell arranged in the first column, and at least one fourth cell arranged in the second column. Each of the first cells has a first cell height along a first direction and is configured to perform a first function. Each of the second cells has a second cell height along the first direction and is configured to perform a second function. The third cell has a third cell height along the first direction and is configured to perform a third function that is different from the first function. The fourth cell has half of the second cell height along the first direction and is configured to perform a fourth function that is different from the second function. Each of the first cells is coupled to and in contact with a respective second cell, and configured to provide at least one signal to the respective second cell according to an input signal. The second cell height is greater than the first cell height, and the number of first cells is equal to the number of second cells. The third cell height is proportional to the first cell height.

Moreover, an embodiment of a method for providing a cell array is provided. The first cell height of a plurality of first cells and the second cell height of a plurality of second cells are obtained. The second cell height is greater than the first cell height. The array height of the cell array is obtained according to a least common multiple of the first cell height and the second cell height. The second cells are arranged in a first column of the cell array. The first cells are arranged in a second column of the cell array. The number of first cells arranged in the second column is equal to the number of second cells arranged in the first column, and each of the second cells is coupled to and in contact with a respective first cell. At least one first additional cell having a third cell height is arranged in the second column of the cell array. Each of the first cells is configured to perform a first function and each of the second cells is configured to perform a second function that is different from the first function. The third cell height is proportional to the first cell height. Each of the first cells comprises an interconnect structure configured to couple to and in contact with a respective second cell.

A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 is a flowchart illustrating a hierarchical design process of an integrated circuit (IC).

FIG. 2 is a simplified diagram illustrating a first cell and a second cell with various cell heights of an IC according to some embodiments of the invention.

FIG. 3 is a simplified diagram illustrating a cell array with hybrid cell height according to some embodiments of the invention.

FIG. 4 A is a simplified diagram illustrating the first cells and the second cells of the cell array in FIG. 3 according to some embodiments of the invention.

FIG. 4 B is a simplified diagram illustrating the device units of the first cell and the device units of the second cell in FIG. 4 A according to some embodiments of the invention.

FIG. 5 is a simplified diagram illustrating a cell array with hybrid cell height according to some embodiments of the invention.

FIG. 6 is a simplified diagram illustrating a cell array with hybrid cell height according to some embodiments of the invention.

FIG. 7 is a simplified diagram illustrating a cell array with hybrid cell height according to some embodiments of the invention.

FIG. 8 is a simplified diagram illustrating a cell array with hybrid cell height according to some embodiments of the invention.

FIG. 9 is a flowchart of a method for providing a cell array with hybrid cell height according to an embodiment of the invention, wherein the method of FIG. 9 is performed by a computer capable of operating an electronic design automation (EDA) tool.

FIG. 10 shows a computer system according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.

Some variations of the embodiments are described. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements. It should be understood that additional operations can be provided before, during, and/or after a disclosed method, and some of the operations described can be replaced or eliminated for other embodiments of the method.

Furthermore, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures.

FIG. 1 is a flowchart illustrating a hierarchical design process of an integrated circuit (IC). In step S 110 , a register-transfer level (RTL) code describing the function performed by the IC is obtained. The RTL code may indicate that a design is performed using a language describing hardware, such as a Hardware Description Language (HDL). In step S 120 , the RTL code is synthesized to generate a netlist including gates (or cells) of the IC. In general, the IC comprises a plurality of blocks, and each block provides a significant function for the IC, such as a specific processor (e.g. an application processor, a video processor, an audio processor, or a controller), a memory (e.g. a SRAM device) and so on. Furthermore, each block has a corresponding RTL code, and then the RTL code of each block is synthesized to generate the corresponding netlist comprising the gates of the block. Before the RTL code is synthesized, a RTL simulation is performed to check the functional correctness of the RTL code. Furthermore, after obtaining the gates of the block in the netlists, a gate level simulation is performed to check the functional correctness of the netlists. In step S 130 , according to the gates of the blocks in the netlists, a placement and routing procedure is performed to generate a layout of whole blocks within a chip area of the IC. Thus, according to the placements, a chip placement and routing procedure is performed and a layout is obtained. In some embodiments, the layout is a whole chip layout. In some embodiments, the layout is a portion of a whole chip layout regarding some digital or analog circuits of the IC. In step S 140 , an analysis procedure is performed and the layout is verified to check whether the layout violates any of the various constraints or rules. After the layout is completed, design rule check (DRC), layout versus schematic (LVS) and electric rule check (ERC) are performed. The DRC is a process of checking whether the layout is successfully completed with a physical measure space according to the design rule, and the LVS is a process of checking whether the layout meets a corresponding circuit diagram. In addition, the ERC is a process of for checking whether devices and wires/nets are electrically well connected therebetween. Furthermore, a post-simulation is performed to check the functional completeness of the layout by extracting and simulating a parasitic component, such as a parasitic capacitance. If there are no violations in the layout, the IC is fabricated (or implemented) according to the layout (step S 150 ). If a violation is present in the layout, the layout of the IC must be modified to handle the violation until no violations are present.

FIG. 2 is a simplified diagram illustrating a first cell 10 and a second cell 20 with various cell heights of an IC according to some embodiments of the invention. The first cell 10 has a cell height H 1 and the second cell 20 has a cell height H 2 in the Y direction, and the cell height H 2 is greater than the cell height H 1 , i.e., H 2 >H 1 . Furthermore, each of the first cells 10 and the second cells 20 includes a plurality of transistors. In some embodiments, the transistors are selected from a group consisting of planar transistors, fin field effect transistors (FinFETs), vertical gate all around (GAA), horizontal GAA, nano wire, nano sheet, or a combination thereof.

In FIG. 2 , the transistors in the first cell 10 are formed by multiple fins 12 that extend in the Y direction, and the transistors in the second cell 20 are formed by multiple fins 22 that extend in the Y direction. In such embodiment, the fin width FW 1 of the fins 12 in the first cell 10 is equal to the fin width FW 2 of the fins 22 in the second cell 20 , i.e., FW 1 =FW 2 . Furthermore, the fin pitch FP 1 of the fins 10 is different from the fin pitch FP 2 of the fins 20 . For example, the fin pitch FP 2 is greater than the fin pitch FP 1 , i.e., FP 2 >FP 1 .

In some embodiments, the fin width FW 1 of the fins 12 in the first cell 10 is different from the fin width FW 2 of the fins 22 in the second cell 20 . For example, the width FW 1 is less than the width FW 2 (i.e., FW 1 <FW 2 ). In some embodiments, the fin pitch FP 1 of the fins 12 is equal to the fin pitch FP 2 of the fins 22 . Moreover, the number of fins 12 in the first cell 10 may be equal to or different from the number of fins 22 in the second cell 20 .

FIG. 3 is a simplified diagram illustrating a cell array 100 A with hybrid cell height according to some embodiments of the invention. The cell array 100 A includes the first cells 10 _ 1 through 10 _ 6 arranged in the first column COL 1 and the second cells 20 _ 1 through 20 _ 6 arranged in the second column COL 2 that is abutting the first column COL 1 . As described above, the cell height H 1 of the first cells 10 _ 1 through 10 _ 6 is less than the cell height H 2 of the second cells 20 _ 1 through 20 _ 6 . Furthermore, the fin pitch FP 1 of the first cells 10 1 through 10 _ 6 is different from the fin pitch FP 2 of the second cells 20 _ 1 through 20 _ 6 . Moreover, the first cells 10 _ 1 through 10 _ 6 and the second cells 20 _ 1 through 20 _ 6 may be the digital cells or analog cells. In some embodiments, the cell height H 1 is in the range from about 130 nm to about 410 nm, and the cell height H 2 is in the range from about 280 nm to about 420 nm.

In FIG. 3 , the cell array 100 A has an array height H_LCM 1 (e.g., 3.64 μm), and the array height H_LCM 1 is determined according to the cell height H 1 and the cell height H 2 . In some embodiments, the array height H_LCM 1 is the least common multiple (LCM) of the cell height H 1 and the cell height H 2 . For example, if the cell height H 1 is 260 nm and the cell height H 2 is 280 nm, the array height H_LCM 1 is the LCM of 260 nm and 280 nm, i.e., 3.64 μm. In some embodiments, the array height H_LCM 1 is the multiple of the LCM of the cell height H 1 and the cell height H 2 .

In the cell array 100 A, each of the first cells 10 _ 1 through 10 _ 6 is a core device configured to perform a first function. Furthermore, the first cells 10 _ 1 through 10 _ 6 have the same circuit configuration. Similarly, each of the second cells 20 _ 1 through 20 _ 6 is an input/output (I/O) device configured to perform a second function. Furthermore, the second cells 20 _ 1 through 20 _ 6 have the same circuit configuration.

In the cell array 100 A, each first cell 10 in the first column COL 1 corresponds to respective second cell 20 in the second column COL 2 , and each first cell 10 is coupled to the corresponding second cell 20 so as to perform the first function and the second function on an input signal to provide an output signal. For example, the first cell 10 _ 1 is configured to perform the first function on an input signal IN 1 to generate at least one intermediate signal to the second cell 20 _ 1 . In respond to the intermediate signal, the second cell 20 _ 1 is configured to perform the second function on the intermediate signal to provide an output signal OUT 1 . Thus, the output signal OUT 1 is obtained according to the input signal IN 1 through a signal path between the first cell 10 _ 1 and the second cell 20 _ 1 . Similarly, the first cell 10 _ 3 is configured to perform the first function on an input signal IN 3 to generate at least one intermediate signal to the second cell 20 _ 3 . In respond to the intermediate signal, the second cell 20 _ 3 is configured to perform the second function on the intermediate signal to provide an output signal OUT 3 . Thus, the output signal OUT 3 is obtained according to the input signal IN 3 through a signal path between the first cell 10 _ 3 and the second cell 20 _ 3 . Specifically, the output signals OUT 1 through OUT 6 are obtained according to the input signals IN 1 through IN 6 through the different signal paths in the cell array 100 A.

In the cell array 100 A, each of the second cells 20 _ 1 through 20 _ 6 is coupled to and in contact with the corresponding first cell 10 . For example, the second cell 20 _ 1 is coupled to and in contact with the first cell 10 _ 1 , the second cell 20 _ 2 is coupled to and in contact with the first cell 10 _ 2 , the second cell 20 _ 3 is coupled to and in contact with the first cell 10 _ 3 , and so on.

In the cell array 100 A, the array height H_LCM 1 is only enough for six second cells 20 , not enough for seven second cells 20 , thus a fourth cell (i.e., an additional cell) 40 having a cell height H 4 is inserted in the second column COL 2 . In such embodiment, the fourth cell 40 is abutting the second cell 20 _ 1 . Furthermore, the cell height H 4 is half of the cell height H 2 . The fourth cell 40 is configured to perform a function that is different from the first function of the first cell 10 and the second function of the second cell 20 . In some embodiment, the fourth cell 40 is a dummy cell or a guard ring cell. In some embodiments, the fourth cell 40 is configured to perform a specific function of a specific circuit different from a circuit including the first cells 10 _ 1 through 10 _ 6 and the second cells 20 _ 1 through 20 _ 6 .

In order to meet the number of second devices 20 that can be placed in the second column COL 2 , only six first devices 10 are arranged in the first column COL 1 . Thus, the third cells (i.e., the additional cells) 30 _ 1 and 30 _ 2 having the cell height H 3 are inserted into the first column COLI. Furthermore, the cell height H 3 is half of the cell height H 1 . In such embodiment, the third cell 30 _ 1 is abutting the first cell 10 _ 1 (e.g., the top of the column COL 1 ), and the third cell 30 _ 2 is abutting the first cells 10 _ 3 and 10 _ 4 (e.g., the middle of the column COL 1 ). Each of the third cells 30 _ 1 and 30 _ 2 is configured to perform a function that is different from the first function of the first cell 10 and the second function of the second cell 20 . In some embodiment, each third cell 30 is a dummy cell or a guard ring cell. In some embodiments, the third cell 30 is configured to perform a specific function of a specific circuit different from a circuit including the first cells 10 _ 1 through 10 _ 6 and the second cells 20 _ 1 through 20 _ 6 .

In the cell array 100 A, the third cells 30 _ 1 and 30 _ 2 function as the filler cells in the first column COL 1 , and the fourth cell 40 function as the filler cells in the second column COL 2 . Thus, no gap (i.e., the empty space) is present in the first column COL 1 and the second column COL 2 , thereby avoiding DRC violations caused by the empty space.

FIG. 4 A is a simplified diagram illustrating the first cells 10 _ 5 and 10 _ 6 and the second cells 20 _ 5 and 20 _ 6 of the cell array 100 A in FIG. 3 according to some embodiments of the invention. Each of the first cells 10 _ 5 and 10 _ 6 includes a plurality of device units 15 and a routing unit 17 . In each first cell 10 , the device units 15 and the routing unit 17 have the cell height H 1 and are arranged in the same row. Furthermore, the device units 15 may have the same or different circuit configuration for perform various operations, and the device units 15 in the same row are configured to perform the first function for the first cell 10 . Similarly, each of the second cells 20 _ 5 and 20 _ 6 includes a plurality of device units 25 . For each second cell 20 , the device units 25 have the cell height H 2 and are arranged in the same row. Furthermore, the device units 25 may have the same or different circuit configuration for perform various operations, and the device units 25 in the same row are configured to perform the second function for the second cell 20 .

In FIG. 4 A , the device units 15 are disposed in a device range 210 and the routing unit 17 is disposed in a routing range 220 in each first cell 10 . Moreover, the device units 25 are disposed in a device range 230 in each second cell 20 . The device range 210 is separated from the device range 230 by the routing range 220 . In other words, the device units 15 are separated from the device units 25 by the routing units 17 . In some embodiments, no transistor is formed in the routing units.

The routing unit 17 has a unit width W 1 in the X direction. The device unit 15 has a unit width W 2 in the X direction, and the unit width W 2 is greater than the unit width W 1 , i.e., W 2 >W 1 . The device unit 25 has a unit width W 3 in the X direction, and the unit width W 3 is also greater than the unit width W 1 , i.e., W 3 >W 1 . In some embodiments, the device units 15 arranged in the same row and corresponding to different operations may have different unit widths, and the device units 25 arranged in the same row and corresponding to different operations may have different unit widths. In some embodiments, the device units 15 arranged in the same row and corresponding to the same operations may have the same unit width, and the device units 25 arranged in the same row and corresponding to the same operations may have the same unit width.

In FIG. 4 A , the first cell 10 _ 5 is configured to perform the first function on an input signal INS to generate the intermediate signals SA 5 and SB 5 to the second cell 20 _ 5 . After receiving the intermediate signals SA 5 and SB 5 , the second cell 20 _ 5 is configured to perform the second function on the intermediate signals SA 5 and SB 5 so as to provide an output signal OUTS. Thus, the output signal OUTS is obtained according to the input signal INS through a signal path between the first cell 10 _ 5 and the second cell 20 _ 5 , and the signal path is formed by the interconnect structures of the device range 210 , the routing range 220 and the device range 230 . For example, the intermediate signal SA 5 is provided to the second cell 20 _ 5 through the interconnect structure 251 of the routing cell 17 , and the intermediate signal SB 5 is provided to the second cell 20 _ 5 through the interconnect structure 252 of the routing cell 17 .

In the device units 15 of the first cell 10 _ 5 , the input signal INS is received through a metal line 271 , and the intermediate signals SA 5 and SB 5 are provided to the interconnect structures 251 and 252 through the metal lines 272 and 273 , respectively. Moreover, the output signal OUTS is provided through a metal line 274 in the device units 25 of the second cell 20 _ 5 . In such embodiments, the metal lines 271 through 274 are formed in a first metal layer. In some embodiments, the metal lines 271 through 274 are formed in various metal layers. In some embodiments, the metal lines in the first cell 10 _ 5 and the second cell 20 _ 5 have different metal widths. For example, a metal width MW 1 of the metal line 271 in the first cell 10 _ 5 is less than a metal width MW 2 of the metal line 274 in the second cell 20 _ 5 . Furthermore, the interconnect structures 251 and 252 are formed by the metal lines in the first metal layer, the metal lines (e.g., 281 ) in a second metal layer over the first metal layer, and the corresponding vias (e.g., 291 ) in a via layer between the first and second metal layers. It should be noted that the configurations of the interconnect structures 251 and 252 are used as an example, and not to limit the invention.

Similarly, the first cell 10 _ 6 is configured to perform the first function on an input signal IN 6 to generate the intermediate signals SA 6 and SB 6 to the second cell 20 _ 6 . After receiving the intermediate signals SA 6 and SB 6 , the second cell 20 _ 6 is configured to perform the second function on the intermediate signals SA 6 and SB 6 to provide an output signal OUT 6 . Thus, the output signal OUT 6 is obtained according to the input signal IN 6 through a signal path between the first cell 10 _ 6 and the second cell 20 _ 6 , and the signal path is formed by the interconnect structures of the device range 210 , the routing range 220 and the device range 230 . For example, the intermediate signal SA 6 is provided to the second cell 20 _ 6 through the interconnect structure 253 of the routing cell 17 , and the intermediate signal SB 6 is provided to the second cell 20 _ 6 through the interconnect structure 254 of the routing cell 17 .

Since the cell height H 1 is different from the cell height H 2 , the first cell 10 _ 5 will not align with the second device 20 _ 5 , and the first cell 10 _ 6 will not align with the second device 20 _ 6 . Thus, the routing cells 17 of two adjacent first cells 10 in the column COL 1 have different interconnect structures. For example, the interconnect structures (e.g., 251 and 252 ) of the routing cell 17 in the first cell 10 _ 5 are different from the interconnect structures (e.g., 253 and 254 ) of the routing cell 17 in the first cell 10 _ 6 , as shown in FIG. 4 A .

FIG. 4 B is a simplified diagram illustrating the device units 15 of the first cell 10 and the device units 25 of the second cell 10 in FIG. 4 A according to some embodiments of the invention.

In the device range 210 of the first cells 10 _ 5 and 10 _ 6 , the power lines 310 and 320 extend along the X direction and are arranged alternately. The power lines 310 and the power lines 320 are configured to connect various power signals. For example, when a power voltage (e.g., VDD) is applied to the power lines 310 , the power lines 320 are grounded. On the contrary, when a power voltage (e.g., VDD) is applied to the power lines 320 , the power lines 310 are grounded.

In the first cell 10 _ 6 , the power lines 310 _ 1 and 310 _ 2 are disposed on the lower and upper sides of the first cell 10 _ 6 , respectively, and the power line 320 _ 1 is disposed between the power lines 310 _ 1 and 310 _ 2 . Moreover, in the first cell 10 _ 5 , the power lines 310 _ 2 and 310 _ 3 are disposed on the lower and upper sides of the first cell 10 _ 5 , respectively, and the power line 320 _ 2 is disposed between the power lines 310 _ 2 and 310 _ 3 . In such embodiment, a pitch of the power lines 310 is equal to a pitch of the power lines 320 . For example, a distance between the power lines 310 _ 1 and 310 _ 2 is equal to the cell height H 1 , and a distance between the power lines 320 _ 1 and 320 _ 2 is also equal to the cell height H 1 . Moreover, in the first cell 10 _ 6 , a distance between the power line 310 _ 1 and the power line 320 _ 1 and a distance between the power line 320 _ 1 and the power line 310 _ 2 are equal to half of the cell height H 1 , i.e., the cell height H 3 . Similarly, in the first cell 10 _ 5 , a distance between the power line 310 _ 2 and the power line 320 _ 2 and a distance between the power line 320 _ 2 and the power line 310 _ 3 are equal to half of the cell height H 1 .

In the device range 230 of the second cells 20 _ 5 and 20 _ 6 , the power lines 315 and 325 extend along the X direction and are arranged alternately. The power lines 315 and the power lines 325 are configured to connect various power signals. For example, when a power voltage (e.g., VDD) is applied to the power lines 315 , the power lines 325 are grounded. On the contrary, when a power voltage (e.g., VDD) is applied to the power lines 325 , the power lines 315 are grounded.

In the second cell 20 _ 6 , the power lines 315 _ 1 and 315 _ 2 are disposed on the lower and upper sides of the second cell 20 _ 6 , respectively, and the power line 325 _ 1 is disposed between the power lines 315 _ 1 and 315 _ 2 . Moreover, in the second cell 20 _ 5 , the power lines 315 _ 2 and 315 _ 3 are disposed on the lower and upper sides of the second cell 20 _ 6 , respectively, and the power line 325 _ 2 is disposed between the power lines 315 _ 2 and 315 _ 3 . In such embodiment, a pitch of the power lines 315 is equal to a pitch of the power lines 325 . For example, a distance between the power lines 315 _ 1 and 315 _ 2 is equal to the cell height H 2 , and a distance between the power lines 325 _ 1 and 325 _ 2 is also equal to the cell height H 2 . Furthermore, in the second cell 20 _ 6 , a distance between the power line 315 _ 1 and the power line 325 _ 1 and a distance between the power line 325 _ 1 and the power line 315 _ 2 are equal to half of the cell height H 2 , i.e., the cell height H 4 . Similarly, in the second cell 20 _ 5 , a distance between the power line 315 _ 2 and the power line 325 _ 2 and a distance between the power line 325 _ 2 and the power line 315 _ 3 are equal to half of the cell height H 2 .

In FIG. 4 B , the power lines 310 and 320 and the power lines 315 and 325 are formed in the same metal layer. Moreover, the power lines 310 and 320 and the power lines 315 and 325 have the same width in the Y direction. In some embodiments, the width of the power lines 310 and 320 is different from the width of the power lines 315 and 325 .

It should be noted that the configuration and arrangement of the power lines 310 and 320 and the power lines 315 and 325 are used as an example, and not to limit the invention. Taking the first cells 10 _ 5 and 10 _ 6 as an example, in some embodiments, multiple power lines 320 are arranged between two adjacent power lines 310 , or multiple power lines 310 are arranged between two adjacent power lines 320 . In some embodiments, the power line 310 is not equidistant from the two adjacent power lines 320 . In some embodiments, the power lines 310 and 320 are formed in different layers. For example, the power lines 310 are formed in a first metal layer, and the power lines 320 are formed in a second metal layer over or under the first metal layer. Moreover, the power lines 310 of the first metal layer may overlay or not overlay the power lines 320 of the second metal layer.

In each device unit 15 , a plurality of transistors are formed in an active region 350 between the bottom power line (e.g., 310 _ 1 ) and the intermediate power line (e.g., 320 _ 1 ), and a plurality of transistors are formed in an active region 355 between the intermediate power line (e.g., 320 _ 1 ) and the top power line (e.g., 310 _ 2 ). In each device unit 25 , a plurality of transistors are formed in an active region 360 between the bottom power line (e.g., 315 _ 1 ) and the intermediate power line (e.g., 325 _ 1 ), and a plurality of transistors are formed in an active region 365 between the intermediate power line (e.g., 325 _ 1 ) and the top power line (e.g., 315 _ 2 ). In some embodiments, the transistors are FinFETs, and the fin width of the transistors in the device range 230 is greater than fin width of the transistors in the device range 210 .

In each of the first cells 10 _ 5 and 10 _ 6 , a plurality of metal lines 330 extending in the X direction are formed over the transistors of the device units 15 . Furthermore, in each of the second cells 20 _ 5 and 20 _ 6 , a plurality of metal lines 340 extending in the X direction are formed over the transistors of the device units 25 . In FIG. 4 B , the metal lines 330 and 340 are formed in the same metal layer. Moreover, the metal lines 330 in the device range 210 and the metal lines 340 in the device range 230 have different metal widths. For example, a metal width MW 3 of the metal line 330 in the first cell 10 _ 5 is less than a metal width MW 4 of the metal line 340 in the second cell 20 _ 5 . Furthermore, the line pitch MP 1 of the metal lines 330 is different from the line pitch MP 2 of the metal lines 340 . For example, the line pitch MP 1 is less than the line pitch MP 2 , i.e., MP 1 <MP 2 .

FIG. 5 is a simplified diagram illustrating a cell array 100 B with hybrid cell height according to some embodiments of the invention. The cell array 100 B includes the first cells 10 _ 1 through 10 _ 6 arranged in the first column COL 1 and the second cells 20 _ 1 through 20 _ 6 arranged in the second column COL 2 that is abutting the first column COL 1 . As described above, the cell height H 1 of the first cells 10 _ 1 through 10 _ 6 is less than the cell height H 2 of the second cells 20 _ 1 through 20 _ 6 .

The cell array 100 B has an array height H_LCM 1 that is equal to the array height H_LCM 1 of the cell array 100 A in FIG. 3 . Compared with the cell array 100 A of FIG. 3 , the third cells 30 _ 1 and 30 _ 2 having the cell height H 3 are arranged in the middle of the first column COL 1 and the fourth cell 40 having the cell height H 4 is arranged in the middle of the second column COL 2 in the cell array 100 B of FIG. 5 . Therefore, the cell array 100 B has a symmetrical configuration in layout along line A-AA. In other words, the routing units 17 and the device units 15 of the first cells 10 _ 1 and 10 _ 6 are mirrored along the line A-AA, the routing units 17 and the device units 15 of the first cells 10 _ 2 and 10 _ 5 are mirrored along the line A-AA, and the routing units 17 and the device units 15 of the first cells 10 _ 3 and 10 _ 4 are mirrored along the line A-AA. Similarly, the device units 25 of the second cells 20 _ 1 and 20 _ 6 are mirrored along the line A-AA, the device units 25 of the second cells 20 _ 2 and 20 _ 5 are mirrored along the line A-AA, and the device units 25 of the second cells 20 _ 3 and 20 _ 4 are mirrored along the line A-AA.

In some embodiments, a single power line 310 and a single power line 320 are disposed on the lower and upper sides of each of the third cells 30 _ 1 and 30 _ 2 , respectively. Furthermore, a distance between the power lines 310 and 320 is equal to the cell height H 3 , i.e., half of the cell height H 1 . Similarly, a single power line 330 and a single power line 340 are disposed on the lower and upper sides of the fourth cell 40 , respectively. Furthermore, a distance between the power lines 330 and 340 is equal to the cell height H 4 , i.e., half of the cell height H 2 .

In the cell array 100 A of FIG. 3 , the routing unit 17 in each of the first cells 10 _ 1 through 10 _ 6 has respective layout configuration due to the asymmetric arrangement of the first cells 10 and the second cells 20 . Compared with the cell array 100 A of FIG. 3 , the cell array 100 B of FIG. 5 has the symmetric arrangement of the first cells 10 and the second cells 20 along the line A-AA, thereby reducing layout costs and process complexity.

FIG. 6 is a simplified diagram illustrating a cell array 100 C with hybrid cell height according to some embodiments of the invention. The cell array 100 C includes the first cells 10 _ 1 through 10 _ 6 arranged in the first column COL 1 and the second cells 20 _ 1 through 20 _ 6 arranged in the second column COL 2 that is abutting the first column COL 1 . As described above, the cell height H 1 of the first cells 10 _ 1 through 10 _ 6 is less than the cell height H 2 of the second cells 20 _ 1 through 20 _ 6 .

In FIG. 6 , the configuration of the cell array 100 C is similar to the configuration of the cell array 100 B in FIG. 5 . The difference between the cell array 100 C of FIG. 6 and the cell array 100 B of FIG. 5 is that the third cells 30 _ 1 and 30 _ 2 having the cell height H 3 are replaced with a fifth cell 50 having the cell height H 1 . Furthermore, the cell array 100 C has a symmetrical configuration in layout along line B-BB. In other words, the first cells 10 _ 1 and 10 _ 6 are mirrored along the line B-BB, the first cells 10 _ 2 and 10 _ 5 are mirrored along the line B-BB, and the first cells 10 _ 3 and 10 _ 4 are mirrored along the line B-BB. Similarly, the second cells 20 _ 1 and 20 _ 6 are mirrored along the line B-BB, the second cells 20 _ 2 and 20 _ 5 are mirrored along the line B-BB, and the second cells 20 _ 3 and 20 _ 4 are mirrored along the line B-BB.

The fifth cell 50 is configured to perform a function that is different from the first function of the first cell 10 and the second function of the second cell 20 . In some embodiment, the fifth cell 50 is a dummy cell or a guard ring cell. In some embodiments, the fifth cell 50 is configured to perform a specific function of a specific circuit different from a circuit including the first cells 10 _ 1 through 10 _ 6 and the second cells 20 _ 1 through 20 _ 6 .

In some embodiments, dual power lines 310 are disposed on the lower and upper sides of the fifth cell 50 , and one power line 320 is disposed between the dual power lines 310 . Furthermore, a distance from each power line 310 to the power line 320 is equal to half of the cell height H 1 .

FIG. 7 is a simplified diagram illustrating a cell array 100 D with hybrid cell height according to some embodiments of the invention. The cell array 100 D includes the first cells 10 _ 1 through 10 _ 6 arranged in the first column COL 1 and the second cells 20 _ 1 through 20 _ 6 arranged in the second column COL 2 that is abutting the first column COL 1 . As described above, the cell height H 1 of the first cells 10 _ 1 through 10 _ 6 is less than the cell height H 2 of the second cells 20 _ 1 through 20 _ 6 .

In FIG. 7 , the configuration of the cell array 100 D is similar to the configuration of the cell array 100 B in FIG. 5 . The difference between the cell array 100 D of FIG. 7 and the cell array 100 B of FIG. 5 is that the third cells 30 _ 1 and 30 _ 2 having the cell height H 3 do not arranged in the middle of the first column COL 1 . In the first column COL 1 , the third cell 30 _ 1 is inserted between the first cells 10 _ 2 and 10 _ 3 , and the third cell 30 _ 2 is inserted between the first cells 10 _ 4 and 10 _ 5 . Similarly, the cell array 100 D has a symmetrical configuration in layout along line C-CC. In other words, the first cells 10 _ 1 and 10 _ 6 are mirrored along the line C-CC, the first cells 10 _ 2 and 10 _ 5 are mirrored along the line C-CC, and the first cells 10 _ 3 and 10 _ 4 are mirrored along the line C-CC. Similarly, the second cells 20 _ 1 and 20 _ 6 are mirrored along the line B-BB, the second cells 20 _ 2 and 20 _ 5 are mirrored along the line B-BB, and the second cells 20 _ 3 and 20 _ 4 are mirrored along the line B-BB.

In some embodiments, the third cell 30 _ 1 is inserted between the first cells 10 _ 1 and 10 _ 2 , and the third cell 30 _ 2 is inserted between the first cells 10 _ 5 and 10 _ 6 in the first column COL 1 .

FIG. 8 is a simplified diagram illustrating a cell array 400 A with hybrid cell height according to some embodiments of the invention. The cell array 400 A includes the sixth cells 60 arranged in the first column COL 1 and the seventh cells 70 arranged in the second column COL 2 that is abutting the first column COL 1 . In such embodiments, the cell height H 5 of the sixth cells 60 is less than the cell height H 6 of the seventh cells 70 . Furthermore, the fin pitch of fins in the sixth cell 60 is different from the fin pitch of fins in the seventh cell 70 . For example, the fin pitch of the sixth cell 60 is less than the fin pitch of the seventh cell 70 . In some embodiments, the cell height H 5 is in the range from about 130 nm to about 410 nm, and the cell height H 6 is in the range from about 280 nm to about 420 nm.

In FIG. 8 , the cell array 400 A has an array height H_LCM 2 , and the array height H_LCM 2 is determined according to the cell height H 5 and the cell height H 6 . In some embodiments, the array height H_LCM 2 is the least common multiple (LCM) of the cell height H 5 and the cell height H 6 . In some embodiments, the array height H_LCM 2 is the multiple of the LCM of the cell height H 5 and the cell height H 6 .

In the cell array 400 A, the sixth cells 60 are core devices configured to perform a third function. Furthermore, the sixth cells 60 have the same circuit configuration. Similarly, the seventh cells 70 are input/output (I/O) devices configured to perform a fourth function. Furthermore, the seventh cells 70 have the same circuit configuration.

Each sixth cell 60 in the first column COL 1 corresponds to respective seventh cell 70 in the second column COL 2 , and each sixth cell 60 is coupled to and in contact with the corresponding seventh cell 70 , so as to perform the third function and the fourth function on an input signal to provide an output signal. Thus, the output signals OUT 1 through OUT 13 are obtained according to the input signals IN 1 through IN 13 through the different signal paths in the cell array 400 A.

In the cell array 400 A, the array height H_LCM 2 can fit 13 seventh cells 70 , thus no additional cells are needed to be inserted into the second column COL 2 . In order to meet the number of seventh cells 70 that can be placed in the second column COL 2 , only 13 sixth devices 60 are arranged in the first column COL 1 . Thus, an eighth cell 80 having the cell height H 5 is inserted into the first column COL 1 .

In the cell array 400 A, the eighth cell 80 functions as the filler cell in the first column COLI. Thus, no gap (i.e., the empty space) is present in the first column COL 1 , thereby avoiding DRC violations caused by the empty space.

FIG. 9 is a flowchart of a method for providing a cell array with hybrid cell height according to an embodiment of the invention, wherein the method of FIG. 9 is performed by a computer capable of operating an electronic design automation (EDA) tool.

First, in step S 510 , the different cell heights of the cells to be arranged in the cell array are obtained, such as the cell height H 1 of the first cell 10 , the cell height H 2 of the first cell 20 , the cell height H 5 of the sixth cell 60 , and the height H 6 of the seventh cell 70 .

In step S 520 , the array height of the cell array is obtained according to the cell heights obtained in step S 510 . In some embodiments, the array height is the least common multiple (LCM) of the different cell heights. In some embodiments, the array height H_LCM 1 is the multiple of the LCM of the different cell heights. In some embodiments, the array height H_LCM 1 is an integer multiple of the LCM of the of the different cell heights.

In step S 530 , the cells having a maximum cell height are arranged in a first column of the cell array. The cells arranged in the first column have the same circuit configuration, and the cells are the same devices configured to perform the same function. Thus, the number of cells having the maximum cell height to be arranged in the first column is determined. If the array height is not an integer multiple of the maximum cell height, one or more additional cells are inserted in the first column to avoid the DRC violations caused by the empty space. As described above, the additional cell may be a dummy cell, a guard ring cell or a cell of other circuit.

In step S 540 , the cells having other cell heights are arranged in other columns of the cell array. For example, the cells having a first cell height are arranged in a second column of the cell array, and the first cell height is different from the maximum cell height. It should be noted that the number of cells having the first cell height in the second column is equal to the number of cells having the maximum cell height in the first column. In some embodiments, the cells having a second cell height are arranged in a third column of the cell array, and the second cell height is different from the maximum cell height and the first cell height. Moreover, the number of cells having the second cell height in the second column is equal to the number of cells having the maximum cell height in the first column. As described above, if the array height of the cell array is not an integer multiple of the first or second cell height, one or more additional cells are inserted in the corresponding column to avoid the DRC violations caused by the empty space.

In step S 550 , the interconnect structures between the cells in different columns are provided. In some embodiments, the interconnect structures are arranged in the specific cells having the cell height less than the maximum cell height and arranged in the same column. As described above, the interconnect structures are arranged in the routing units 17 of the specific cells.

After the interconnect structures and the cells having the different cell heights are placed in the cell array, the cell array may has a asymmetrical configuration (e.g., the cell array 100 A of FIG. 3 and the cell array 400 A of FIG. 8 ) or a symmetrical configuration (e.g., the cell array 100 B of FIG. 5 , the cell array 100 C of FIG. 6 and the cell array 100 D of FIG. 7 ) in layout.

FIG. 10 shows a computer system 600 according to an embodiment of the invention. The computer system 600 comprises a computer 610 , a display device 620 and a user input interface 630 , wherein the computer 610 comprises a processor 640 , a memory 650 , and a storage device 660 . The computer 610 is coupled to the display device 620 and the user input interface 630 , wherein the computer 610 is capable of operating an electronic design automation (EDA) tool. Furthermore, the computer 610 is capable of receiving input instructions or information (e.g. timing constraints, RTL code, or interface information of the memory device) from the user input interface 630 and displaying simulation results, the layout of the IC and the blocks or circuits of the layout on the display device 620 . In some embodiments, the display device 620 is a GUI for the computer 610 . Furthermore, the display device 620 and the user input interface 630 can be implemented in the computer 610 . The user input interface 630 may be a keyboard, a mouse, and so on. In the computer 610 , the storage device 660 can store the operating systems (OSs), applications, information (e.g. circuit function information and power-related information) and data that comprise input required by the applications and/or output generated by applications. The processor 640 of the computer 610 can perform one or more operations (either automatically or with user input) in any method that is implicitly or explicitly described in this disclosure. For example, during an operation, the processor 640 can load the applications of the storage device 660 into the memory 650 , and then the applications can be used by the user to create, view, and/or edit a placement, a floor plan and a physical layout for a circuit design (e.g., the cell array with hybrid cell height).

The data structures and code described in this disclosure can be partially or fully stored on a computer-readable storage medium and/or a hardware module and/or hardware apparatus. A computer-readable storage medium may be, but is not limited to, volatile memory, non-volatile memory, magnetic and optical storage devices such as disk drives, magnetic tape, CDs (compact discs), DVDs (digital versatile discs or digital video discs), or other media, now known or later developed, that are capable of storing code and/or data. Examples of hardware modules or apparatuses described in this disclosure include, but are not limited to, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), dedicated or shared processors, and/or other hardware modules or apparatuses now known or later developed.

While the invention has been described by way of example and in terms of the preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.